The reduction in the rate of caesarean section is a major public health issue, it has reached 21% in 2010 Fance. Indeed complications to expect during pregnancy and childbirth increase doubles the risk of fetal morbidity, néonatal and maternal history of when césareinne. recommendations for clinical practice (RPC) to "scarred uterus" are being drafted under the auspices of the National College of obstetrics and gynecology (CNGOF) well highlighting the health problem public this represents. During 2011, 15% of the 2,700 patients who have recently given birth to the north of Marseille Hospital were carriers of a scarred uterus (internal data).The objective of the obstetrician is to ensure the welfare mother and fetus at the end of pregnancy and childbirth. To do this, the realization of a work being cesarean allows in some cases to reduce neonatal morbidity related to workflow especially in case of abnormal fetal pericardial pace that suggest fetal hypoxia. However, a significant number of caesarean section is performed by the side of caution during the second part of the work to a suspicion of non-engagement of the fetal presentation. These caesareans are indicated, rightly, before a clinical doubt about the height of the engagement of the fetal presentation in order to avoid making a difficult instrumental delivery, potentially harmful to the mother (perineal tear 3rd and 4th degree) and fetus (head injury, intracranial hemorrhage, cephalohematoma). A prospective study published in the Lancet estimated 37% error percentage attributable to the clinical examination in case of doubt on the commitment of presenatation fœtale. The CNGOF held through PRC publication what to do in case of obstetric clinical doubt about the commitment of the fetal presentation and "not recommended" no show against an instrumental extraction in this situation (RPC 2008).